The difference between Discard and Junk

When used as nouns, discard means anything discarded, whereas junk means discarded or waste material.

When used as verbs, discard means to throw away, to reject, whereas junk means to throw away.

check bellow for the other definitions of Discard and Junk

Discard as a verb (transitive):

to throw away, to reject.
Discard as a verb (intransitive, card games):

To make a discard; to throw out a card.
Discard as a verb:

To dismiss from employment, confidence, or favour; to discharge.

Discard as a noun:

Anything discarded.
Discard as a noun:

A discarded playing card in a card game.
Discard as a noun (programming):

A temporary variable used to receive a value of no importance and unable to be read later.

Junk as a noun:

Discarded or waste material; rubbish, trash.
Junk as a noun:

A collection of miscellaneous items of little value.
Junk as a noun (slang):

Any narcotic drug, especially heroin.
Junk as a noun (slang):

The clothed genitalia.
Junk as a noun (nautical):

Salt beef.
Junk as a noun:

Pieces of old cable or cordage, used for making gaskets, mats, swabs, etc., and when picked to pieces, forming oakum for filling the seams of ships.
Junk as a noun (dated):

A fragment of any solid substance; a thick piece; a chunk.

Examples:

"rfquotek Lowell"

Junk as a verb (transitive):

To throw away.
Junk as a verb (transitive):

To find something for very little money (meaning derived from the term junk shop)

Examples:

"(On Facebook, a record collector wrote:) "The newest addition to my Annette Hanshaw collection, I junked this beautiful flawless E-copy within walking distance from my house."